This disclosure is generally in the field of controlled drug delivery, and more particularly in the field of implantable medical devices for controlled drug release and drug formulations for use with implantable medical devices.
A variety of devices and methods have been developed to deliver drug locally or regionally to mitigate problems associated with systemic drug delivery. Local delivery of drug to some tissue sites could be improved, however, particularly with respect to extended drug delivery from devices that are less invasive and uncomfortable for the patient.
Some treatments could be improved by implanting a drug delivery device in a body lumen or cavity such as the bladder. For example, interstitial cystitis (IC), painful bladder syndrome (PBS), and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) are chronic painful disorders that are often treated by delivering a lidocaine solution to the bladder via instillation, but the frequent instillations required for sustained relief entail inconvenience, discomfort, and the risk of infection associated with urinary catheterization. Similarly, the symptoms of neurogenic bladder may be treated by delivering drugs to the bladder via intermittent catheterization, which carries the drawbacks described above, among others. These and other therapeutic or prophylactic treatments, including those for acute post-operative pain, could benefit from drug delivery devices for implantation in the bladder, particularly where local or regional drug delivery is sought, such as when the side effects of systemic drug delivery are intolerable or when bioavailability from oral administration is too low.
Implantable drug delivery devices for the bladder are known but suffer from one or more deficiencies. Some such known devices are loaded with a drug solution, which are capable only of carrying and releasing a relatively smaller amount of drug than what could be delivered in a less voluminous form, such as without a solvent or carrying fluid for the drug. An example is the UROS infuser device by Situs Corporation, as disclosed in U.S. Pat. Nos. 6,171,298, 6,183,461, and 6,139,535, which can deliver pharmaceutical solutions of, for example, oxybutynin for the treatment of overactive bladder or mitomycin C for the treatment of bladder cancer. It would be desirable to provide drug delivery systems and devices that provide higher ratios of drug volume: device volume.
Conventional solid dosage forms are primarily designed for oral administration and systemic delivery, not local delivery to the bladder. Solid drug forms may not be suited for loading into implantable devices, particularly tiny devices of millimeter or micrometer scales, such as in a manner that is consistent and repeatable. Furthermore, these solid dosage forms are not designed to be sterilized or to be provided in sterile packaging.
Accordingly, a need exists for an improved implantable drug delivery device, for example, that is sufficiently small to reduce discomfort and pain associated with deployment and retention, that can reduce the number of surgical or interventional procedures required for implantation and delivery of drug over the treatment period, that can provide controlled delivery over an extended period, that can carry an effective amount of drug for the extended period in a sufficiently small payload volume, and that can be retained in the bladder or other vesicle or lumen without excretion or elimination until the drug payload is at least substantially released, even when the drug is delivered over a period of days or weeks.